Summary:
First batch of adding more tests to ASSERT_STATUS_CHECKED.

* db_iterator_test
* db_memtable_test
* db_merge_operator_test
* db_merge_operand_test
* write_batch_test
* write_batch_with_index_test

Pull Request resolved: https://github.com/facebook/rocksdb/pull/7679

Reviewed By: ajkr

Differential Revision: D25399270

Pulled By: pdillinger

fbshipit-source-id: 3017d0a686aec5cd2d743fc2acbbf75df239f3ba

Summary:
To build on FreeBSD, arch_ppc_probe needs to be adapted to FreeBSD.

Since FreeBSD uses elf_aux_info as an getauxval equivalent, use it and include necessary headers:
- machine/cpu.h for PPC_FEATURE2_HAS_VEC_CRYPTO,
- sys/auxv.h for elf_aux_info,
- sys/elf_common.h for AT_HWCAP2.

elf_aux_info isn't checked for being available, because it's available since FreeBSD 12.0. rocksdb assumes using Clang on FreeBSD, but powerpc* platforms switch to Clang only since 13.0.

This patch makes rocksdb build on FreeBSD on powerpc64 and powerpc64le platforms.

Pull Request resolved: https://github.com/facebook/rocksdb/pull/7732

Reviewed By: ltamasi

Differential Revision: D25399194

Pulled By: pdillinger

fbshipit-source-id: 9c905147d75f98cd2557dd2f86a940b8e6c5afcd

Summary: Pull Request resolved: https://github.com/facebook/rocksdb/pull/7750

Reviewed By: ltamasi

Differential Revision: D25400609

Pulled By: pdillinger

fbshipit-source-id: 13b15e2f490acc011b648fbd9615ea8e580cccc7

Summary:
Consider the case:
1. All column families are flushed, so all WALs become obsolete, but no WAL is removed from disk yet because the removal is asynchronous, a VersionEdit is written to MANIFEST indicating that WALs before a certain WAL number are obsolete, let's say this number is 3;
2. `SyncWAL` is called, so all the on-disk WALs are synced, and if track_and_verify_wal_in_manifest=true, the WALs will be tracked in MANIFEST, let's say the WAL numbers are 1 and 2;
3. DB crashes;
4. During DB recovery, when replaying MANIFEST, we first see that WAL with number < 3 are obsolete, then we see that WAL 1 and 2 are synced, so according to current implementation of `WalSet`, the `WalSet` will be recovered to include WAL 1 and 2;
5. WAL 1 and 2 are asynchronously deleted from disk, then the WAL verification algorithm fails with `Corruption: missing WAL`.

The above case is reproduced in a new unit test `DBBasicTestTrackWal::DoNotTrackObsoleteWal`.

The fix is to maintain the upper bound of the obsolete WAL numbers, any WAL with number less than the maintained number is considered to be obsolete, so shouldn't be tracked even if they are later synced. The number is maintained in `WalSet`.

Pull Request resolved: https://github.com/facebook/rocksdb/pull/7725

Test Plan:
1. a new unit test `DBBasicTestTrackWal::DoNotTrackObsoleteWal` is added.
2. run `make crash_test` on devserver.

Reviewed By: riversand963

Differential Revision: D25238914

Pulled By: cheng-chang

fbshipit-source-id: f5dccd57c3d89f19565ec5731f2d42f06d272b72

Summary:
This PR removes a nested loop inside ProcessManifestWrites. The new
implementation has the same behavior as the old code with simpler logic
and lower complexity.

Pull Request resolved: https://github.com/facebook/rocksdb/pull/7751

Test Plan:
make check
Run make crash_test on devserver and succeeds 3 times.

Reviewed By: ltamasi

Differential Revision: D25363526

Pulled By: riversand963

fbshipit-source-id: 27e681949dacd7501a752e5e517b9e85b54ccb2e

Summary:
This PR has two commits:
1.  Modify the code to allow different Lock Managers (of any kind) to be used.  It is implied that a LockManager uses its own custom LockTracker.
2.  Add definitions for Range Locking (class Endpoint and GetRangeLock() function.

cheng-chang, is this what you've had in mind (should the PR have both item 1 and item 2?)

Pull Request resolved: https://github.com/facebook/rocksdb/pull/7443

Reviewed By: zhichao-cao

Differential Revision: D24123172

Pulled By: cheng-chang

fbshipit-source-id: c6548ad6d4cc3c25f68d13b29147bc6fdf357185

Summary:
This change eliminates the need for a lot of the PermitUncheckedError calls on return from ErrorHandler methods.  The calls are no longer needed as the status is returned as a reference rather than a copy.  Additionally, this means that the originating status (recovery_error_, bg_error_) is not cleared implicitly as a result of calling one of these methods.

For this class, I do not know if the proper behavior should be to call PermitUncheckedError in the destructor or if the checked state should be cleared when the status is cleared.  I did tests both ways.  Without the code in the destructor, the status will need to be cleared in at least some of the places where it is set to OK.  When running tests, I found no instances where this class was destructed with a non-OK, non-checked Status.

Pull Request resolved: https://github.com/facebook/rocksdb/pull/7539

Reviewed By: anand1976

Differential Revision: D25340565

Pulled By: pdillinger

fbshipit-source-id: 1730c035c81a475875ea745226112030ec25136c

Summary:
`googletest` uses exceptions to communicate assertion failures when
`GTEST_THROW_ON_FAILURE` is set, which does not go well with
`std::thread`s, since an exception escaping the top-level function of an
`std::thread` object or an `std::thread` getting destroyed without
having been `join`ed or `detach`ed first results in a call to
`std::terminate`. The patch fixes this by moving the `Status` assertions
of background operations in `ExternalSstFileTest.PickedLevelBug` to the
main thread.

Pull Request resolved: https://github.com/facebook/rocksdb/pull/7754

Test Plan: `make check`

Reviewed By: riversand963

Differential Revision: D25383808

Pulled By: ltamasi

fbshipit-source-id: 32fb2721e5169ec898d218900bc0d83eead45d03

Summary:
This PR adds a fuzzer to the project and infrastructure to integrate Rocksdb with OSS-Fuzz. OSS-Fuzz is a service run by Google that performs continuous fuzzing of important open source projects. The LevelDB project is also in being fuzzed by OSS-Fuzz (https://github.com/google/oss-fuzz/tree/master/projects/leveldb). Essentially, OSS-Fuzz will perform the fuzzing for you and email you bug reports, coverage reports etc. All we need is a set of email addresses that will receive this information.

For cross-referencing, the PR that adds the OSS-Fuzz logic is here: https://github.com/google/oss-fuzz/pull/4642

The `db_fuzzer` of the PR performs stateful fuzzing of Rocksdb by calling a sequence of Rockdb's APIs with random input in each fuzz iteration. Each fuzz iteration, thus, creates a new instance of Rocksdb and operates on this given instance. The goal is to test diverse states of Rocksdb and ensure no state lead to error conditions, e.g. memory corruption vulnerabilities.

The fuzzer is similar (although more complex) to the fuzzer that is currently being used to analyse Leveldb (https://github.com/google/oss-fuzz/blob/master/projects/leveldb/fuzz_db.cc)

Pull Request resolved: https://github.com/facebook/rocksdb/pull/7674

Reviewed By: pdillinger

Differential Revision: D25238536

Pulled By: cheng-chang

fbshipit-source-id: 610331c49a77eb68d3b1d7d5ef1b0ce230ac0630

Summary:
Handle misuse of snprintf return value to avoid Out of bound
read/write.

Pull Request resolved: https://github.com/facebook/rocksdb/pull/7686

Test Plan: make check -j64

Reviewed By: riversand963

Differential Revision: D25030831

Pulled By: akankshamahajan15

fbshipit-source-id: 1a1d181c067c78b94d720323ae00b79566b57cfa

Summary:
Buck TARGETS files are sometimes parsed with Python, and sometimes with Starlark - this TARGETS file was not Starlark compliant. In Starlark you can't have a top-level if in a TARGETS file, but you can have a ternary `a if b else c`. Therefore I converted TARGETS, and updated the generator for it.

Pull Request resolved: https://github.com/facebook/rocksdb/pull/7743

Reviewed By: pdillinger

Differential Revision: D25342587

Pulled By: ndmitchell

fbshipit-source-id: 88cbe8632071a45a3ea8675812967614c62c78d1

Summary:
Added a fix for the failure of
DBTest2.PartitionedIndexUserToInternalKey on ppc64le in travis
Closes https://github.com/facebook/rocksdb/issues/7746

Pull Request resolved: https://github.com/facebook/rocksdb/pull/7752

Test Plan:
Ran travis job multiple times and it passed. Will keep
watching the travis job after this patch.

Reviewed By: pdillinger

Differential Revision: D25373130

Pulled By: akankshamahajan15

fbshipit-source-id: fa0e3f85f75b687415044a506e42cc38ead87975

Summary:
Following https://github.com/facebook/rocksdb/issues/7655 and https://github.com/facebook/rocksdb/issues/7657, this PR adds `full_history_ts_low_` to `ColumnFamilyData`.
`ColumnFamilyData::full_history_ts_low_` will be used to create `FlushJob` and `CompactionJob`.

`ColumnFamilyData::full_history_ts_low` is persisted to the MANIFEST file. An application can only
increase its value. Consider the following case:

>
> The database has a key at ts=950. `full_history_ts_low` is first set to 1000, and then a GC is triggered
> and cleans up all data older than 1000. If the application sets `full_history_ts_low` to 900 afterwards,
> and tries to read at ts=960, the key at 950 is not seen. From the perspective of the read, the result
> is hard to reason. For simplicity, we just do now allow decreasing full_history_ts_low for now.
>

During recovery, the value of `full_history_ts_low` is restored for each column family if applicable. Note that
version edits in the MANIFEST file for the same column family may have `full_history_ts_low` unsorted due
to the potential interleaving of `LogAndApply` calls. Only the max will be used to restore the state of the
column family.

Pull Request resolved: https://github.com/facebook/rocksdb/pull/7740

Test Plan: make check

Reviewed By: ltamasi

Differential Revision: D25296217

Pulled By: riversand963

fbshipit-source-id: 24acda1df8262cd7cfdc6ce7b0ec56438abe242a

Summary:
Add macos+cmake build on CircleCI instead.

Pull Request resolved: https://github.com/facebook/rocksdb/pull/7745

Test Plan: CI

Reviewed By: riversand963

Differential Revision: D25352864

Pulled By: pdillinger

fbshipit-source-id: 6b0a328cbe715bc3b43d70e919a27c834edcf079

Summary:
The patch adds iterator support to the integrated BlobDB implementation.
Whenever a blob reference is encountered during iteration, the corresponding
blob is retrieved by calling `Version::GetBlob`, assuming the `expose_blob_index`
(formerly `allow_blob`) flag is *not* set. (Note: the flag is set by the old stacked
BlobDB implementation, which has its own blob file handling/blob retrieval logic.)

In addition, `DBIter` now uniformly returns `Status::NotSupported` with the error
message `"BlobDB does not support merge operator."` when encountering a
blob reference while performing a merge (instead of potentially returning a
message that implies the database should be opened using the stacked BlobDB's
`Open`.)

TODO: We can implement support for lazily retrieving the blob value (or in other
words, bypassing the retrieval of blob values based on key) by extending the `Iterator`
API with a new `PrepareValue` method (similarly to `InternalIterator`, which already
supports lazy values).

Pull Request resolved: https://github.com/facebook/rocksdb/pull/7731

Test Plan: `make check`

Reviewed By: riversand963

Differential Revision: D25256293

Pulled By: ltamasi

fbshipit-source-id: c39cd782011495a526cdff99c16f5fca400c4811

Summary:
In current code base, in FlushMemtable, when `(Flush_reason == FlushReason::kErrorRecoveryRetryFlush && (!cfd->mem()->IsEmpty() || !cached_recoverable_state_empty_.load()))`, we assert that cfd->imm()->NumNotFlushed() > 0. However, there are some corner cases that can fail this assert: 1) if there are multiple CFs, some CF has immutable memtable, some CFs don't. In ResumeImpl, all CFs will call FlushMemtable, which will hit the assert. 2) Regular flush is scheduled and running, the resume thread is waiting. New KVs are inserted and SchedulePendingFlush is called. Regular flush will continue call MaybeScheduleFlushAndCompaction until all the immutable memtables are flushed. When regular flush ends and auto resume thread starts to schedule new flushes, cfd->imm()->NumNotFlushed() can be 0.

Remove the assert and added the comments.

Pull Request resolved: https://github.com/facebook/rocksdb/pull/7744

Test Plan: make check and pass the stress test

Reviewed By: riversand963

Differential Revision: D25340573

Pulled By: zhichao-cao

fbshipit-source-id: eac357bdace660247c197f01a9ff6857e3c97672

Summary:
Closes - https://github.com/facebook/rocksdb/issues/7710

I tested this on an Apple DTK (Developer Transition Kit) with an Apple A12Z Bionic CPU and macOS Big Sur (11.0.1).

Previously the arm64 specific CRC optimisations were limited to Linux only OS... Well now Apple Silicon is also arm64 but runs macOS ;-)

Pull Request resolved: https://github.com/facebook/rocksdb/pull/7714

Reviewed By: ltamasi

Differential Revision: D25287349

Pulled By: pdillinger

fbshipit-source-id: 639b168bf0ac2652907531e9604936ac4974b577

Summary:
In error_handler auto recovery case, if recovery_in_prog_ is false, the recover is finished or failed. In this case, the auto recovery thread should finish its execution so recovery_thread_ should be null. However, in some cases, it is not null, the caller should not directly returned. Instead, it should wait for a while and create a new thread to execute the new recovery.

Pull Request resolved: https://github.com/facebook/rocksdb/pull/7700

Test Plan: make check, error_handler_fs_test

Reviewed By: anand1976

Differential Revision: D25098233

Pulled By: zhichao-cao

fbshipit-source-id: 5a1cba234ca18f6dd5d1be88e02d66e1d5ce931b

Summary:
When 2 phase commit is enabled, if there are prepared data in a WAL, the WAL should be kept, the minimum log number for such a WAL is written to MANIFEST during flush. In atomic flush, such information is not written to MANIFEST.

Pull Request resolved: https://github.com/facebook/rocksdb/pull/7570

Test Plan: Added a new unit test `DBAtomicFlushTest.ManualFlushUnder2PC`, this test fails in atomic flush without this PR, after this PR, it succeeds.

Reviewed By: riversand963

Differential Revision: D24394222

Pulled By: cheng-chang

fbshipit-source-id: 60ce74b21b704804943be40c8de01b41269cf116

Summary:
Update check_format_compatible.sh with 6.15.fb

Pull Request resolved: https://github.com/facebook/rocksdb/pull/7738

Reviewed By: ajkr

Differential Revision: D25307717

Pulled By: ramvadiv

fbshipit-source-id: 49f5c6366e8c8a2ade9697975453c9c65e919f1b

Add kManifestWriteNoWAL to BackgroundErrorReason to handle Flush IO Error when WAL is disabled (#7693)

Summary:
In the current code base, all the manifest writes with IO error will be set with reason: BackgroundErrorReason::kManifestWrite, which will be mapped to the kHardError if the IO Error is retryable. However, if the system does not use the WAL, all the retryable IO error should be mapped to kSoftError. Create this PR to handle is special case by adding kManifestWriteNoWAL to BackgroundErrorReason.

Pull Request resolved: https://github.com/facebook/rocksdb/pull/7693

Test Plan: make check, add new testing cases to error_handler_fs_test

Reviewed By: anand1976

Differential Revision: D25066204

Pulled By: zhichao-cao

fbshipit-source-id: d59553896c2eac3fb37c05238544d2b265379462

Summary:
The minimum rate check in RateLimiterTest.Rate can fail in
Facebook's CI system Sandcastle, presumably due to heavily loaded
machines. This change disables the minimum rate check for Sandcastle
runs, and cleans up the code disabling it on other CI environments. (The
amount of conditionally compiled code shall be minimized.)

Pull Request resolved: https://github.com/facebook/rocksdb/pull/7728

Test Plan: try new test with and without setting envvar SANDCASTLE=1

Reviewed By: ltamasi

Differential Revision: D25247642

Pulled By: pdillinger

fbshipit-source-id: d786233af37af9a874adbb3a9e2707ec52c27a5a

Summary:
Add timestamp to the `CompactRange()` and `GetApproximateSizes` range keys if needed.

Pull Request resolved: https://github.com/facebook/rocksdb/pull/7684

Test Plan: make check

Reviewed By: riversand963

Differential Revision: D25015421

Pulled By: jay-zhuang

fbshipit-source-id: 51ca0756087eb053a3b11801e5c7ce1c6e2d38a9

Summary:
https://github.com/facebook/rocksdb/issues/7340 reports and reproduces an assertion failure caused by a combination of the following:
- atomic flush is disabled.
- a column family can appear multiple times in the flush queue at the same time. This behavior was introduced in release 5.17.

Consequently, it is possible that two flushes race with each other. One bg flush thread flushes all memtables. The other thread calls `FlushMemTableToOutputFile()` afterwards, and hits the assertion error below.

```
  assert(cfd->imm()->NumNotFlushed() != 0);
  assert(cfd->imm()->IsFlushPending());
```

Fix this by reverting the behavior. In non-atomic-flush case, a column family can appear in the flush queue at most once at the same time.

Pull Request resolved: https://github.com/facebook/rocksdb/pull/7362

Test Plan:
make check
Also run stress test successfully for 10 times.
```
make crash_test
```

Reviewed By: ajkr

Differential Revision: D25172996

Pulled By: riversand963

fbshipit-source-id: f1559b6366cc609e961e3fc83fae548f1fad08ce

Summary:
Timestamp should not be included in prefix extractor, as we discussed here: https://github.com/facebook/rocksdb/pull/7589#discussion_r511068586

Pull Request resolved: https://github.com/facebook/rocksdb/pull/7668

Test Plan: added unittest

Reviewed By: riversand963

Differential Revision: D24966265

Pulled By: jay-zhuang

fbshipit-source-id: 0dae618c333d4b7942a40d556535a1795e060aea

Summary:
Closes https://github.com/facebook/rocksdb/issues/7691

The optimised CRC code for PPC64le which was originally imported in https://github.com/facebook/rocksdb/pull/2353 is not compatible with Clang 11. It looks like the code most likely originated from https://github.com/antonblanchard/crc32-vpmsum.

The code relied on a GCC header file `ppc-asm.h` which is not available in Clang.

To solve this, I have taken the same approach as the the upstream project from which the CRC code came https://github.com/antonblanchard/crc32-vpmsum/commit/ffc8018efc1e4f05d22a9fc8dde57109dd09368b#diff-ec3e62c56fbcddeb07230f2a4673c1abd7f0f1cc8e48a2aa560056cfc1b25d60 and simply imported a copy of the GCC header file into our code-base which will be used when Clang is the compiler on pcc64le.

**NOTE**: The new file `util/ppc-asm.h` may have licensing implications which I guess need to be approved by RocksDB/Facebook before this is merged

Pull Request resolved: https://github.com/facebook/rocksdb/pull/7713

Reviewed By: jay-zhuang

Differential Revision: D25222645

Pulled By: pdillinger

fbshipit-source-id: e3fec9136f26ce1eb7a027048bcf77a6cb3c769c

Summary:
TSAN reports that our stack trace handler makes unsafe calls
during a signal handler. I just tried fixing some of them and I don't
think it's fixable unless we can get away from using FILE stdio. Even if
we can use lower level functions only, I'm not sure it's fixed.

I also tried suppressing the reports with function and file level TSAN
suppression, but that doesn't seem to work, perhaps because the
violation is reported on the callee, not the caller.

So I added a warning to be printed whenever these violations would be
reported that they are practically ignorable.

Internal ref: T77844138

Pull Request resolved: https://github.com/facebook/rocksdb/pull/7723

Test Plan:
run external_sst_file_test with seeded abort(), with TSAN
(TSAN warnings + new warning) and without TSAN (no warning, just stack
trace).

Reviewed By: akankshamahajan15

Differential Revision: D25228011

Pulled By: pdillinger

fbshipit-source-id: 3eda1d6e7ca3cdc64076cf99ae954168837d2818

Summary:
WAL may be truncated to an incomplete record due to crash while writing
the last record or corruption. In the former case, no hole will be
produced since no ACK'd data was lost. In the latter case, a hole could
be produced without this PR since we proceeded to recover the next WAL
as if nothing happened. This PR changes the record reading code to
always report a corruption for incomplete records in
`kPointInTimeRecovery` mode, and the upper layer will only ignore them
if the next WAL has consecutive seqnum (i.e., we are guaranteed no
hole).

While this solves the hole problem for the case of incomplete
records, the possibility is still there if the WAL is corrupted by
truncation to an exact record boundary. This PR also regresses how much data
can be recovered when writes are mixed with/without
`WriteOptions::disableWAL`, as then we can not distinguish between a
seqnum gap caused by corruption and a seqnum gap caused by a `disableWAL` write.

Pull Request resolved: https://github.com/facebook/rocksdb/pull/7701

Test Plan:
Interestingly there already was a test for this case
(`DBWALTestWithParams.kPointInTimeRecovery`); it just had a typo bug in
the verification that prevented it from noticing holes in recovery.

Reviewed By: anand1976

Differential Revision: D25111765

Pulled By: ajkr

fbshipit-source-id: 5e330b13b1ee2b5be096cea9d0ff6075843e57b6

Summary: Pull Request resolved: https://github.com/facebook/rocksdb/pull/7716

Reviewed By: pdillinger

Differential Revision: D25214340

Pulled By: zhichao-cao

fbshipit-source-id: 143a8e7d076917e60bbe6993d60ec55f33e2ab56

Summary:
The patch adds basic garbage collection support to the integrated BlobDB
implementation. Valid blobs residing in the oldest blob files are relocated
as they are encountered during compaction. The threshold that determines
which blob files qualify is computed based on the configuration option
`blob_garbage_collection_age_cutoff`, which was introduced in https://github.com/facebook/rocksdb/issues/7661 .
Once a blob is retrieved for the purposes of relocation, it passes through the
same logic that extracts large values to blob files in general. This means that
if, for instance, the size threshold for key-value separation (`min_blob_size`)
got changed or writing blob files got disabled altogether, it is possible for the
value to be moved back into the LSM tree. In particular, one way to re-inline
all blob values if needed would be to perform a full manual compaction with
`enable_blob_files` set to `false`, `enable_blob_garbage_collection` set to
`true`, and `blob_file_garbage_collection_age_cutoff` set to `1.0`.

Some TODOs that I plan to address in separate PRs:

1) We'll have to measure the amount of new garbage in each blob file and log
`BlobFileGarbage` entries as part of the compaction job's `VersionEdit`.
(For the time being, blob files are cleaned up solely based on the
`oldest_blob_file_number` relationships.)
2) When compression is used for blobs, the compression type hasn't changed,
and the blob still qualifies for being written to a blob file, we can simply copy
the compressed blob to the new file instead of going through decompression
and compression.
3) We need to update the formula for computing write amplification to account
for the amount of data read from blob files as part of GC.

Pull Request resolved: https://github.com/facebook/rocksdb/pull/7694

Test Plan: `make check`

Reviewed By: riversand963

Differential Revision: D25069663

Pulled By: ltamasi

fbshipit-source-id: bdfa8feb09afcf5bca3b4eba2ba72ce2f15cd06a

Summary:
This PR updates `MemTable::Add()`, `MemTable::Update()`, and
`MemTable::UpdateCallback()` to return `Status` objects, and adapts the
client code in `MemTableInserter`. The goal is to prepare these
functions for key-value checksum, where we want to verify key-value
integrity while adding to memtable. After this PR, the memtable mutation
functions can report a failed integrity check by returning `Status::Corruption`.

Pull Request resolved: https://github.com/facebook/rocksdb/pull/7656

Reviewed By: riversand963

Differential Revision: D24900497

Pulled By: ajkr

fbshipit-source-id: 1a7e80581e3774676f2bbba2f0a0b04890f40009

Summary:
These new unit tests should ensure that we don't accidentally
change the interpretation of bits for what I call Standard128Ribbon
filter internally, available publicly as NewExperimentalRibbonFilterPolicy.
There is very little intuitive reason for the values we check against in
these tests; I just plug in the right expected values upon watching the
test fail initially.

Most (but not all) of the tests are essentially "whitebox" "round-trip." We
create a filter from fixed keys, and first compare the checksum of those
filter bytes against a saved value. We also run queries against other fixed
keys, comparing which return false positives against a saved set.

Pull Request resolved: https://github.com/facebook/rocksdb/pull/7696

Test Plan: test addition and refactoring only

Reviewed By: jay-zhuang

Differential Revision: D25082289

Pulled By: pdillinger

fbshipit-source-id: b5ca646fdcb5a1c2ad2085eda4a1fd44c4287f67

Summary:
Allow corruption_test to run on custom env loaded via
`Env::LoadEnv()`.

Pull Request resolved: https://github.com/facebook/rocksdb/pull/7699

Test Plan:
```
make corruption_test
./corruption_test
```

Also run on in-house custom env.

Reviewed By: zhichao-cao

Differential Revision: D25135525

Pulled By: riversand963

fbshipit-source-id: 7941e7ce342dc88ec2cd63e90f7674a2f57de6b7

Summary:
Fix initialization order of DBOptions and kHostnameForDbHostId by making the initialization of the latter static rather than dynamic.

Pull Request resolved: https://github.com/facebook/rocksdb/pull/7702

Reviewed By: ajkr

Differential Revision: D25111633

Pulled By: anand1976

fbshipit-source-id: 7afad834a66e40bcd8694a43b40d378695212224

Summary:
Updates the option description and HISTORY.

Pull Request resolved: https://github.com/facebook/rocksdb/pull/7689

Test Plan: N/A

Reviewed By: zhichao-cao

Differential Revision: D25056238

Pulled By: cheng-chang

fbshipit-source-id: 6af1ef6f8dcf2173cbc0fccadc0e06cefd92bcae

Summary:
Hi there,

This PR fixes a few typos in comments in `cache/lru_cache.h`.

Thanks

Pull Request resolved: https://github.com/facebook/rocksdb/pull/7687

Reviewed By: ajkr

Differential Revision: D25064674

Pulled By: jay-zhuang

fbshipit-source-id: fe633369d5b82c5aac42d4ee8d551b9d657237d1

Summary:
An empty WAL won't be backed up by the BackupEngine. So if we track the empty WALs in MANIFEST, then when restoring from a backup, it may report corruption that the empty WAL is missing, which is correct because the WAL is actually in the main DB but not in the backup DB, but missing an empty WAL does not logically break DB consistency.

Pull Request resolved: https://github.com/facebook/rocksdb/pull/7697

Test Plan: watch existing tests to pass

Reviewed By: pdillinger

Differential Revision: D25077194

Pulled By: cheng-chang

fbshipit-source-id: 01917b57234b92b6063925f2ee9452c5732bdc03

Summary:
It's worth mentioning the corner case bug fixed in PR 7621.

Pull Request resolved: https://github.com/facebook/rocksdb/pull/7690

Test Plan: N/A

Reviewed By: zhichao-cao

Differential Revision: D25056678

Pulled By: cheng-chang

fbshipit-source-id: 1ab42ec080f3ffe21f5d97acf65ee0af993112ba

Summary:
Add cmake-mignw in circle-build

Pull Request resolved: https://github.com/facebook/rocksdb/pull/7144

Test Plan: watch circle cmake-mingw build

Reviewed By: jay-zhuang

Differential Revision: D25039744

Pulled By: akankshamahajan15

fbshipit-source-id: 92584c9d5ad161b93d5e5a1303aac306e7985108

Summary:
The logic for computing min_log_number_to_keep in atomic flush was incorrect.

For example, when all column families are flushed, the min_log_number_to_keep should be the latest new log. But the incorrect logic calls `PrecomputeMinLogNumberToKeepNon2PC` for each column family, and returns the minimum of them. However, `PrecomputeMinLogNumberToKeepNon2PC(cf)` assumes column families other than `cf` are flushed, but in case all column families are flushed, this assumption is incorrect.

Without this fix, the WAL referenced by the computed min_log_number_to_keep may actually contain no unflushed data, so the WAL might have actually been deleted from disk on recovery, then an incorrect error `Corruption: missing WAL` will be reported.

Pull Request resolved: https://github.com/facebook/rocksdb/pull/7660

Test Plan:
run `make crash_test_with_atomic_flush`  on devserver
added a unit test in `db_flush_test`

Reviewed By: riversand963

Differential Revision: D24906265

Pulled By: cheng-chang

fbshipit-source-id: 08deda62e71f67f59e3b7925cdd86dd09bd4f430